As a power transmission device constituted to include a pair of one-way clutches and capable of switching the transmitting direction of power (power transmission device), for example, one disclosed in Japanese Application Publication No. H10-323257 is known. In the power transmission device disclosed in this publication, relative rotation of an outer ring and a shaft is locked by engaging elements constituting a one-way clutch. The locked state of the relative rotation is released by operating an operation lever and moving an engaging/disengaging operation member that holds the engaging elements, and is switched to an idling state.